It is known that silent discharge occurs when disposing a dielectric between two electrodes and applying a high alternating current voltage or a periodic pulsed voltage between the electrodes and that, in the resulting plasma field, active species, radicals, and ions are produced to promote reaction and decomposition of gas. This phenomenon may be utilized to remove toxic components contained in engine exhaust gas or incinerator exhaust gas.
For example, a plasma exhaust gas treatment system has been disclosed in which NOx, carbon fine particles, HC, and CO contained in engine exhaust gas or incinerator exhaust gas is oxidized by causing the engine exhaust gas or incinerator exhaust gas to pass through plasma (e.g. JP-A-2001-164925).